Privacy enhancement for Internet electronic mail: Part I: Message encipherment and authentication proceduresThis RFC is the Outgrowth of a series of IAB Privacy Task Force meetings and of internal working papers distributed for those meetings. This memo defines message encipherment and authentication procedures, as the initial phase of an effort to provide privacy enhancement services for electronic mail transfer in the Internet. Detailed key management mechanisms to support these procedures will be defined in a subsequent RFC. As a goal of this initial phase, it is intended that the procedures defined here be compatible with a wide range of key management approaches, including both conventional (symmetric) and public-key (asymmetric) approaches for encryption of data encrypting keys. Use of conventional cryptography for message text encryption and/or integrity check computation is anticipated.